Method of and agent for depilating hides



Patented Jan. 14 1930 UNITED"STATESA PATENT, OFFICE EDWARD A. TAYLOR, OFCLEVELAND, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

THE GRASSELLI CHEMICAL COMPANY, OF

DELAWARE No Drawing.

to the objection that the hides so depilated often do not possess thefull plumpness desired, and that an undue period of time, generallyabout six days, is consumed in the depilation. This refers to theregular beam house practice where the hair is recovered.

' When rapid dehairing is desired without recovery of the hair, it isnecessary to use a very appreciable quantity of sodium sulfide,

but this procedure has certain undesirable effects on the hides, such asoverplumpness, harshness of grain, and other characteristics of the sotreated hides.

I have now found a process whereby the period of time necessary for thedepilation, without saving the hair, may be shortened to the same timeaswhen using a large excess of sulfide and still secure a desirablyfull, solid plumpness of the stock. This process consists substantiallyin depilating the hides in a watery mixture comprising milk of lime anda hydrosulfide, to which mixture a relatively small amount of analkaline metal sufide has been added. The hydrosulfides found useful inthis process are those of the alkali metals, alkaline earth metals,and/or ammonium hydrosulfide, such as hydrosulfides of sodium, calcium,ammonium, or the like. Such a depilating agent has been found to have adepilatory strength many times that of the agents heretofore used, thusmaking possible the complete removal of hair from ordinary hides andeven difiicultly depilated hides in a very short time. The hides sotreated show no destruction of the grain, or diminution of CLEVELAND,OHIO, A CORPORATION OF METHOD OF AND AGENT FOR DEPILATING HIDESApplication filed February 4, 1928. Serial No. 252,053.

fide to be admixed with the milk of lime and sodium sulfide, I havefound that very rapid depilatory action obtains by the use of suchproportions where the hydrosulfide is in molecular excess overthealkaline sulfide as represented, for instance, by a solu tion containingabout 2 by weight of lime, from 1 to 1%% by weight of sodiumhydrosulfide, and from .5 to .7 of sodium sulfide, the amounts beingbased on the weight of the green, wet hides .undergoing the depilatorytreatment. Treatment of hides with depilatory agents of this strengthresults in complete removal of all hair within three to five hours. Theattack of the hair starts at the tip which curls up and the hair iscompletely destroyed and removed in the above relatively short time. Theinvention will be described more fully byrecourse to, the followingexample, it being understood that the invention is not limited to theuse of any particular alkaline hydrosulfide or to" the exact proportionsand/or conditions hereinafter set out: 2,700# of well washed steer hideswere introduced into a, paddle wheel containing 2,700 gallons of waterin which were dis solved '67.5# lime, 17.5# sodium sulfide, and 44.5#sodium hydrosulfide. After paddling for 10 minutes, the hair of thehides showed evidence of curling. Atthe end of 3 hours treatment, thehides were found to be free of all hair, including the difficultyattacked ground hairs. The hides were .then separated from thedepilating agent using hides depilated by my novel process.

Repetition of the aboveoperation in which I there was substituted forthe sodium hydrosulfide, calcium hydrosulfide and ammonium hydrosulfide,respectively, established the fact that the depilatory action is notdependent upon the particular alkali radical but is dependent upon thehydrosulfide radical in combination with the earth alkali metalhydroxide and alkali metal sulfide.

One-half of the depilating agents used in the above bath is consumed bythe depilatory action. The liquor, after removal of the hair, can besweetened and used for subsequent operations by adding thereto one-halfof the original amounts of lime, hydrosulfide and sulfide. g

It a pears that the ratio of hydrosulfide to sulfide is; important forobtaining the-full successful results of my process, but the presence ofboth hydrosulfide and sulfide is also essential. Hydrosulfide and limealone will not produce complete depilation in a short time; the additionof sodium sulfide thereto is essential for successful removal of thehair. I Y

For the practical application of my novel process it is sometimesadvisable to furnish the tanner with a tanning compound containing thesodium sulfide and sodium hydrosulfide mixed in the correct proportions.This is easily! produced by mixing concentrated solutions of sodiumsulfide or other alkali metal sulfides with the hydrosulfide andconcentrating these solutions to high percentage of solids, usually 60to 75% active Ingredients, the balance consisting principally ofcombined water. Such mixed products have the same physical appearance asordinary fused sodium sulfide and dissolve readily in water.

A very useful depilating salt contains a molecular ratio of sodiumsulfide to sodium hydrosulfide of 1:2 or higher. Such intimate mixturescontaining sodium sulfide and hydrosulfide in molecular ratios as highas 1: 5 can easily be prepared in this manner, and I prefer to use saltscontaining the active ingredient within the above limits as theycorrespond to the proportions most useful in carrying out my noveldepilating process. It is to be understood that for purposes of thisinvention the hydroxide of an alkaline earth metal is the functionalequivalent of an oxide of said alkaline earth metal. For example, it isobvious that a dry composition suitable for solution in water to theformation of a depilatory solution may be prepared from an alkalineearth metal oxide, an alkaline metal sulfide, and the hydrosulfide of analkali or alkaline earth metal, and that said composition in aqueoussolution will contain the h droxide rather than the oxide of thealkallne earth metal. Therefore, in the appended claims, the namesalkaline earth metal oxide and lime (calcium oxide) embrace both thehydrated and non-hydrated oxides. Likewise, it is to be understood thatby the expressions alkaline sulfides and alkaline hydrosulfides Iintendto include respectively sulfides and hydrosulfides of the strongbase-forming elements or radicals such as sodi m,

potassium, calcium, magnesium, and ammomum.

I claim:

1. Process of depilating hides which comprises treating the hides withan aqueous solution obtained by dissolving in water an alkaline earthmetal oxide, an alkaline sulfide, and an alkaline hydrosulfide.

2. Process of depilating hides which comprises treating the hides withan aqueous solution obtained by dissolving in water milk of lime, analkaline sulfide, and an alkaline hydrosulfide, the molecular amount ofhyggosulfide being in excess of that of the sul- 3. Process ofdepilating hides which comprises treating the hides with an aqueoussolution obtained by dissolving in water milk of lime, sodium sulfide,and sodium hydrosulfide, the molecular amount of the hydrosulfide beingin excess of that of the sulfide.

4. Process of depilating hides which comprises treating the hides withan aqueous solution obtained by dissolving in water 25 parts of lime,6.5 parts of sodium sulfide, and 16.5 parts of sodium hydrosulfide foreach thousand parts of green, wet hides. 5. As a composition of matteruseful for the preparation of a depilating bath, an intimate mixture ofsodium sulfide and sodium hydrosulfide in which the molecular ratio ofthe sulfide to the hydrosulfide is within the limits of about 1:2 and1:5.

In testimony whereof I aflix my signature.

- EDWARD A. TAYLOR.

